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4. Giant fishes from the Bahariya Formation, Bahariya Oasis, Western Desert, Egypt

Author

Grandstaff, Barbara Smith and Grandstaff, Barbara Smith

Abstract

The Cenomanian (early Late Cretaceous) Bahariya Formation of Egypt preserves a diverse fauna of marine and freshwater fishes. Fish remains recovered from this formation at Bahariya Oasis include a very large polypterid and a very large mawsoniid coelacanth. Generic identity of the polypterid remains unclear. The discovery of new mawsoniid material provides an opportunity to re-examine Mawsonia libyca, for which the type material has been lost. The amount of freshwater input to the Cenomanian environment at Bahariya Oasis has been variously interpreted. Histological sections of scales were used to confirm that the presumed polypterid fish from Bahariya is a polypterid. Comparative anatomy and biomechanical analysis were used to study the polypterid and mawsoniid fishes. The habitat preferences of extant relatives of the fish and other fossil taxa preserved at Bahariya Oasis were examined to provide information about the paleoenvironment in which the Cenomanian Bahariya fauna lived. Depositional environments of the Bahariya sediments, and the environments in which fossil relatives of the Bahariya taxa are preserved at other sites, were also used to gain a greater understanding of the paleoenvironment preserved at Bahariya Oasis. Histologic sections confirmed that polypterid scales from Bahariya have the four tissue layers characteristic of polypterids: ganoin, dentine, isopedine, and bone. The polypterid scales and ectopterygoid from Bahariya are morphologically distinct from those of Polypterus. The mawsoniid remains from Bahariya belong to Mawsonia libyca, a species originally described from the Oasis. Remains of his giant (three meter long) coelacanth are widespread in the Oasis, suggesting it lived in the paralic environment where its remains were buried. Mawsonia libyca was an active predator with a large gape, and could have preyed on many of the fishes known in the Bahariya fauna. Based on the presence of lungfish and large polypterids, as well as crocodilians

Published
2006

6. LUNGFISHES FROM THE TRINITY GROUP (CRETACEOUS) OF NORTH TEXAS.

Author

Parris, David C., Grandstaff, Barbara Smith, and Banks, Nathan T.

Subjects
*AUSTRALIAN lungfish, *INVERTEBRATES, *PREDATION, *DENTITION, *ANIMAL species
Abstract

Most Ceratodus specimens from the Aptian/Albian of north Texas belong to a small species that is characterized by distinctive sharp dental crests, denticulate in unworn tooth plates. These blade-like crests, indicative of a cutting and chopping dentition, distinguish this lineage from the crushing dentitions of most other North American Cretaceous dipnoans. This species is described and named herein as Ceratodus texanus. The functional adaptation of the dentition of this species (cutting/chopping) is indicative of predation on small invertebrates. The species is recorded from the Antlers Formation at Butler Farm (Wise County) and Greenwood Canyon (Montague County), and from the Twin Mountains Formation at the Jones Ranch Locality (Hood County). Although the natural history of dipnoans in the eastern North American subcontinent remains largely unknown, it is now certain that eastern lungfish populations, after formation of the central seaway, included lineages with crushing dentitions and lineages with sectorial dentitions. [ABSTRACT FROM AUTHOR]

Published
2011

7. A NEW LUNGFISH (DIPNOI: CERATODONTIDAE) FROM THE CRETACEOUS WOODBINE FORMATION, ARLINGTON ARCHOSAUR SITE, NORTH TEXAS.

Author

Main, Derek J., Parris, David C., Grandstaff, Barbara Smith, and Carter, Bradley

Abstract

A significant number of lungfish dentitions are now known from the Cretaceous (Cenomanian) Woodbine Formation, primarily from one new locality, the Arlington Archosaur Site of northeast Tarrant County, Texas. The Arlington Archosaur Site preserves a diverse coastal ecosystem within the interbedded coals, mudstones and sand lenses of a delta plain environment. The new lungfish specimens pertain to previously undescribed species from the Cenomanian. Previously recorded from but one specimen, this taxon is now represented by both prearticular and pterygopalatine dental plates of sectorial aspect. This species is similar to, and presumably descended from, one that has been previously recorded from various formations of Albian age. Measurements of the angles of the dental plate margins and crests confirm that it is distinct. Two small specimens appear to represent an earlier ontogenetic stage. Although dipnoan evolution generally appears to have proceeded slowly, the taxa from the Cretaceous (Albian -- Cenomanian) of Texas may possibly provide some stratigraphic indices, based on what is now known. The new Woodbine lungfish is herein referred to a new species; Ceratodus carteri. [ABSTRACT FROM AUTHOR]

Published
2011

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